This invention relates generally to self-leveling supports, and in particular to self-leveling support assemblies for household appliances such as washing machines.
Household appliances of many kinds are generally required to be supported in a level position for proper operation. Because many floor surfaces are not flat and level, it is generally necessary to provide leveling means at each corner of the appliance. Since the appliance must generally be supported at each of the four corners of the base, one approach to provide such support is to use screw-type legs threaded into the base at each of the four corners so that the legs may be raised and lowered individually to level the appliance and provide sufficient support at each corner.
The problem is particularly acute in the case of washing machines, not only because they are relatively heavy and undergo strong vibrating forces which can become quite high when the washing machine is in the spin mode, but also because they are generally used on particularly uneven floors, suchas in a basement or utility room, where the floors are intentionally sloped to provide for proper drainage. Furthermore, the leveling problem is complicated by the fact that in many locations, a washing machine, in particular, is so positioned that the rear legs are not easily accessible for leveling purposes, and it is therefore sometimes necessary to move the washing machine in and out of the position between trial adjustments until proper extension of the rear legs is achieved.
To overcome this problem, it has been proposed to make some of the legs, and in particular the two rear legs, of a washing machine remotely adjustable from the front of the machine or to provide a self-leveling arrangement in which the extension of the two rear legs can be automatically compensated for when the machine is leveled by the front screw-adjusted legs alone. One such arrangement is shown in U.S. Pat. No. 3,304,032, where the two rear legs are rigidly interconnected by a center section, and the unit then secured to the machine frame, using a pin and angled slot arrangement. With this construction, a certain amount of self-leveling is achieved by the interconnection between the two rear legs, so that as one leg may be raised, the other one is automatically extended. Thus, when the machine is put on a surface that slopes downwardly toward one side or the other of the machine, the two rear legs will remain in contact with the floor and support the rear of the machine at both rear corners, and the transverse leveling, as well as the front-to-back leveling, is then accomplished entirely by two screw legs at the two front corners of the washing machine. Such an arrangement has generally proven satisfactory for leveling purposes, but requires that the total height of the machine when shipped be increased by the average extension of the two legs, which is variable only as to each other and not as to the total height of the machine. Since this arrangement increases the height of the machine when shipped, and therefore requires greater space, it is often proposed that the entire mechanism be rmeoved during shipment and reinstalled only before the machine is installed at its place of operation.
One method of overcoming the above problem regarding shipping is shown in U.S. Pat. No. 4,262,870, in which the legs are made with a mechanism that allows them to be stored in a retracted position to allow minimum height of the washing machine, and for installation a retaining mechanism is removed to allow the legs, if the back of the machine is raised, to move downwardly into an operating position, where they may be automatically reconnected together to provide a leveling action similar to that disclosed in U.S. Pat. No. 3,304,032. However, the mechanism of the latter-mentioned patent becomes complex and expensive, requiring a plurality of parts and a spring action to allow the extension and interlocking of the legs when the machine in unpacked and prior to installation.